稀土富过渡族金属化合物的形成条件、晶体结构和磁性能(Ⅱ)

Formation,Crystal Structure and Magnetic Properties of Rare-Earth Transition-Metal Intermetallic Compounds

稀土(R)富过渡族金属(T)化合物是探索新型稀土永磁材料的主要研究对象,其磁性能与晶体结构密切相关。本文系统综述了我们近年来针对二元化合物不存在的情况下,通过第三组元M的稳定作用,合成和稳定具有CaCu5型衍生结构的化合物Rm-nT5m+2n(包括R(T,M)7,R2(T,M)17,R3(T,M)29和R(T,M)12),具有NaZn13型结构的化合物R(T,M)13,以及m层RT5和n层RT3B2组合的化合物Rm+nT5m+3nB2n等方面的主要研究结果。重点讨论了这些化合物的晶体结构、形成条件和磁性能,阐述了加入M对化合物的稳定作用机制,及M的晶体学占位对磁性能的影响。研究结果表明:M的加入不仅能够起到稳定化合物的作用,往往还可以显著改善化合物的磁性能。

The rare-earth （ R ） transition-metal （ T ） compounds are main research object for searching new hard magnets. The magnetic properties of these com- pounds are highly dependent on their crystal struc- tures. In this contribution, we summarized our recent progress in synthesis and stabilization of Rm_nTsm＋2,, compounds derived from the CaCu5-type structure （in- cludingR（T,M）7, R2（T,M）17, R3（T,M）29 and R（T,M） 12）, R（T,M）13 compounds with the NaZn13- type structure, and Rm＋n,T5m＋3nB2n compounds with m layers of RTs and n layers of RT3B2 by adding the third element M, especially in the case that the binary compound did not exist. Our investigation was empha- sized on the formation, crystal structure and magnetic properties of these compounds. The effect of the third element M on the phase stability and the atomic occu- pation of M on the magnetic properties were illustra- ted. According to our experimental results, the addi- tion of the third element M could not only stabilize the compound but also improve the magnetic properties.